1. Field of the Invention
The present invention relates to a method for a developing processing of a substrate such as a semiconductor wafer subjected to an exposure treatment and an apparatus for supplying a developing solution.
2. Description of the Related Art
In a manufacturing process of a semiconductor device, a prescribed circuit pattern is formed on the surface of a semiconductor wafer by using a so-called xe2x80x9cphotolithography technologyxe2x80x9d. In the photolithography step, a series of treatments are carried out such that a resist film is formed on a cleaned semiconductor wafer by supplying a photoresist solution onto the semiconductor wafer, followed by exposing the resist film to light in a prescribed pattern and subsequently developing the pattern.
In the developing step, an exposed semiconductor wafer is held first by a rotatable spin chuck. Then, a puddle of a developing solution is formed by supplying a developing solution onto the surface of a semiconductor wafer held stationary by the spin chuck, and the developing solution supplied onto the surface of the semiconductor wafer is left to stand for a prescribed time so as to permit the developing reaction to proceed. In the next step, a rinsing liquid such as a pure water is supplied onto the semiconductor wafer while rotating the semiconductor wafer so as to rinse the semiconductor wafer. Finally, the supply of the rinsing liquid onto the semiconductor wafer is stopped, and the semiconductor wafer is rotated at a high speed so as to dry the semiconductor wafer by a spin drying. In this case, a TMAH solution having a fixed concentration of, for example, 2.38% by weight for the various resist materials is used as the developing solution.
Strictly speaking, however, the appropriate concentration of the developing solution differs for each resist material. Further, the appropriate concentration of the developing solution is changed with the reaction time during the developing reaction. It was possible in the past to obtain the required accuracy in, for example, the shape of the circuit pattern even if a developing solution having a predetermined concentration is used for a plurality of different resist materials. In recent years, however, a resist material having a high reactivity to the developing solution has come to be used. Further, the resist film has come to be formed thinner. Further, the light having a shorter wavelength has come to be used for the exposure, and the pattern exposed to light has been made finer and finer. Under the circumstances, it is difficult nowadays to form a satisfactory circuit pattern by the conventional method for the developing processing using a developing solution of a predetermined concentration.
Further, in the conventional method for the developing processing, which is carried out with the semiconductor wafer held stationary, a dissolved product formed by the developing reaction, which dissolves the resist film, remains in a high concentration in a part on the surface of the semiconductor wafer. Therefore, in the latter stage of the developing processing, the state of equilibrium between the dissolved product remaining in a high concentration and the developing solution is collapsed, with the result that the dissolved product is diffused toward the developing solution. It is possible for the movement of the developing solution accompanying the diffusion of the dissolved product to bring about a change in a partial critical dimension (CD), i.e., the line width of the pattern, on the wafer surface. Further, if the developing solution and the dissolved product are removed by rotating the wafer simultaneously with start-up of the supply of a rinsing liquid after the developing processing, the dissolved product leaves their traces on the wafer surface when the dissolved product of a high concentration is centrifugally expanded. Naturally, the traces of the dissolved product left on the wafer surface degrades the wafer.
As described above, the dissolved product of the resist affects the CD in the latter stage of the developing processing. What should be noted is that, since the generating amount of the dissolved product differs depending on the aperture rate of the mask, the CD distribution on the wafer surface is rendered different depending on the aperture rate of the mask in spite of the same pattern. Further, the CD in the central portion is rendered different from that in the outer circumferential portion within a single shot. In conclusion, in the conventional method for the developing processing, the CD uniformity on the substrate is not necessarily satisfactory. It was customary in the past to deal with the problem by, for example, correcting the pattern of the mask under the prescribed conditions for the developing processing. However, it is highly laborious to determine appropriately the conditions for the developing processing.
What should also be noted is that, if a pure water is supplied onto a semiconductor wafer after completion of the developing reaction, the pH value of the developing solution on the semiconductor wafer is rapidly lowered, with the result that the dissolved product is precipitated in the form of a solid material so as to be attached to the developing pattern, thereby generating a defect.
A first object of the present invention is to provide an appropriate method for a developing processing conforming to the characteristics of the resist material relative to the developing solution. A second object of the present invention is to provide a method for a developing processing with an improved CD uniformity. A third object of the present invention is to provide a method for a developing processing, which permits suppressing the defect generation caused by the precipitation of the dissolved product in the form of a solid material during the developing processing. Further, a fourth object of the present invention is to provide an apparatus for supplying a developing solution used in the method of the present invention for the developing processing.
According to a first aspect of the present invention, there is provided a method for a developing processing of a resist film formed on a substrate, said resist film being applied to an exposure treatment, said method comprising steps of:
adjusting the concentration of a developing solution in accordance with the characteristics of said resist film; and
applying a developing processing to said resist film using said concentration-adjusted developing solution.
According to a second aspect of the present invention, there is provided a method of a resist film formed on a substrate, said resist film being applied to an exposure treatment, said method comprising the steps of:
supplying a first developing solution onto said substrate;
leaving the substrate having said first developing solution supplied thereto to stand for a prescribed time so as to permit a developing reaction to proceed;
further supplying a second developing solution differing from said first developing solution in concentration onto said substrate;
leaving the substrate having said second developing solution supplied thereto to stand for a prescribed time so as to permit a developing reaction to proceed; and
rinsing the substrate having said second developing solution supplied thereto.
In the method for the developing processing according to each of the first and second aspects of the present invention, it is possible to carry out the developing processing by using a developing solution having an appropriate concentration conforming to the characteristics of the resist film relative to the developing solution. Further, since the step for the developing processing can be finely controlled by, for example, using a plurality of developing solutions differing from each other in the concentration, it is possible to obtain a circuit pattern satisfactory in, for example, the accuracy of the shape.
According to a third aspect of the present invention, there is provided a method for a developing processing of a resist film formed on a substrate, said resist film being applied to an exposure treatment, said method comprising the steps of:
supplying a first developing solution onto the surface of said substrate;
leaving the substrate having said first developing solution supplied thereto to stand for a prescribed time to permit a developing reaction to proceed;
supplying a second developing solution onto the substrate having said first developing solution supplied thereto;
leaving the substrate having said second developing solution supplied thereto to stand for a prescribed time so as to permit the concentration of the dissolved product formed by the developing reaction of said first developing solution to be lowered by said second developing solution; and
rinsing the substrate having said second developing solution supplied thereto.
According to a fourth aspect of the present invention, there is provided a method for a developing processing of a resist film formed on a substrate, said resist film being applied to an exposure treatment, said method comprising the steps of:
supplying a developing solution onto said substrate;
leaving the substrate having said developing solution supplied thereto to stand for a prescribed time so as to permit a developing reaction to proceed;
supplying a liquid that does not dissolve a resist film or a liquid low in the dissolving power of the resist film onto the substrate having said developing solution supplied thereto;
leaving the substrate having said liquid supplied thereto to stand for a prescribed time so as to permit the concentration of the dissolved product formed by said developing solution to be lowered by said liquid; and,
rinsing the substrate having said liquid supplied thereto.
In the method for the developing processing according to each of the third and fourth aspects of the present invention, the concentration of the dissolved product is lowered so as to prevent the generation of the traces of the development and, thus, to improve the quality. Further, it is possible to improve the CD uniformity on the substrate surface. Particularly, in the method for the developing processing according to the fourth aspect of the present invention, it is desirable to use a liquid, which does not change rapidly the pH value of the developing solution supplied onto the substrate, as the liquid used for the coating after supply of the developing solution onto the substrate. In this case, it is possible to suppress generation of the defect caused by the precipitation in the form of a solid material of the dissolved product derived from the rapid change in the pH value of the developing solution supplied onto the substrate.
According to the present invention, provided is an apparatus for supplying a developing solution, which can be suitably employed in the method of the present invention for the developing processing described above. To be more specific, according to a fifth aspect of the present invention, there is provided an apparatus for supplying a developing solution onto a substrate, comprising:
a developing solution spurting nozzle having a long shape in one direction and serving to spurt a developing solution in substantially a band shape in the longitudinal direction thereof;
a first liquid supply device for supplying a developing solution having a prescribed concentration into said developing solution spurting nozzle; and
a second liquid supply device for supplying a pure water or a developing solution differing in concentration from the developing solution supplied from said first liquid supply device into said developing solution spurting nozzle;
wherein said developing solution spurting nozzle comprises:
a first liquid reservoir for storing the developing solution supplied from said first liquid supply device;
a second liquid reservoir for storing the pure water or the developing solution supplied from said second liquid supply device;
a liquid mixing chamber having a developing solution spurting port for spurting a developing solution or a pure water formed in the lower end and communicating with said first liquid reservoir and said second liquid reservoir;
a first communicating passageway for allowing said first liquid reservoir to communicate with said liquid mixing chamber; and
a second communicating passageway for allowing said second liquid reservoir to communicate with said liquid mixing chamber, and
wherein said developing solution, said pure water and said developing solution having a different concentration are separately spurted from said developing solution spurting port, or the developing solution stored in said first liquid reservoir is mixed with the pure water or the developing solution having a different concentration, which is stored in said second liquid reservoir, in said liquid mixing chamber so as to prepare a developing solution having a prescribed concentration, said developing solution, which has a prescribed concentration, being spurted from said developing solution spurting port.
Further, according to a sixth aspect of the present invention, there is provided an apparatus for supplying a developing onto a substrate, comprising:
a developing solution spurting nozzle having a long shape in one direction and serving to spurt the developing solution in substantially a band shape in the longitudinal direction thereof;
a developing solution supply device for supplying a developing solution having a prescribed concentration into said developing solution spurting nozzle; and
a plurality of liquid supply devices for separately supplying a plurality of different kinds of liquid materials into said developing solution spurting nozzle,
wherein said developing solution spurting nozzle comprises:
a developing solution reservoir for storing the developing solution supplied from said developing solution supply device;
a plurality of liquid reservoirs for separately storing a plurality of different kinds of liquid materials supplied from said plural liquid supply devices;
a liquid mixing chamber having a liquid spurting port for spurting a developing solution or said plural kinds of liquid materials formed in the lower end and communicating with said developing solution reservoir and with said plural liquid reservoirs;
a first communicating passageway for allowing said developing solution reservoir to communicate with said liquid mixing chamber; and
a second communicating passageway for allowing each of said plural liquid reservoirs to communicate with said liquid mixing chamber, and
wherein said developing solution and said plural different kinds of liquid materials are spurted separately from said liquid spurting port, or at least two kinds of liquid materials selected from said plural kinds of different materials are mixed in said liquid mixing chamber so as to prepare a prescribed liquid material, which is spurted from said liquid spurting port.
According to the particular apparatus for supplying a developing solution of the present invention, it is possible to adjust the concentration of the developing solution easily. Further, since it is unnecessary to arrange a plurality of nozzles in accordance with the concentration of the developing solution, the construction of the apparatus can be simplified.